Fans having radial flow rotors in axial flow casings



Aug. 27, 1963 R. 1.. CARLSON 3, 0

FANS HAVING RADIAL FLOW ROTORS IN AXIAL FLOW CASINGS Filed May 29, 19612 Sheets-Sheet 1 Izweniva'tfl gyiizoazd L 0123 550321, 6%

fliiorneg V Aug. 27, 1963 R. L. CARLSON 3,101,890

FANS HAVING RADIAL FLOW ROTORS IN AXIAL FLOW CASINGS Filed May 29, 19612 Sheets-Sheet 2 laweeaifor llaymzadlifiafihow,

United States Patent 3,101,890 FANS HAVING RADIAL FLOW RDTORS 1N AXIALFLOW CASINGS Raymond L. Carlson, Canton, Mass, assignor to WestinghouseElectric Corporation, East Pittsburgh, Pa., 2 corporation ofPennsylvania Filed May 29, 1961, Ser. No. 126,377

3 Claims. (Cl. 230-427) This invention relates to fans having radialflow rotors in axial flow-casings, and has as objects to cool thebearings of such rotors, and to provide seals for preventing gaseshandled by such fans from escaping into the rooms where the fans arelocated.

In fans having radial flow rotors in outer axial flow casings, it iscustomary to support the shafts of the rotors and the bearings for theshafts, within inner casings behind the rotors. Such fans are often usedto handle hot and con taminated gases which may overheat their bearings,and which may escape into the rooms in which the fans are located.

This invention uses the hub of the rotor of such a fan as an auxiliaryfan which draws in room air to cool the bearings, and to form an airseal to prevent the escape of gas along the rotor shaft into the roomwhere the fan is located. hub has radial slots formed in its back sidefor forming radial passages between it and the back plate of the rotor.In another embodiment of this invention, a series of passage producingholes is provided through the hub from its back side to its front side,and uniformly spaced apart around the shaft. The passages so formed, actas auxiliary fan blades.

This invention will now be described with reference to the annexeddrawings, of which:

'FIG. 1 is a side section of a fan embodying this invention;

FIG. 2 is an enlarged section of the hub, the rotor back plate, theupstream end Wall of the inner casing, and the seal rings between theback plate and the end wall, of FIG. 1;

FIG. 3 is a section along the lines 33 of FIG. 2;

FIG. 4 is a view similar to FIG. 2 but showing a hub having differentlyformed auxiliary fan passages, and

FIG. 5 is a section along the lines 55 of FIG. 4.

Referring to the drawings, a generally cylindrical outer casing has itsupstream Wall 11 turned inwardly to form an inwardly converging,conical, gas inlet passage 12 connected to a gas supply duct 13. Thecasing 10 has at its downstream end, a converging wall 14 for-med as afrustrum of a cone, which is connected to a gas outlet duct 15. Thecasing '10 is supported on a base 16.

An inner casing 17 has a cylindrical upstream portlon '18, and aconverging downstream wall 19 shaped as a frustrum of a cone, supportedfrom and concentric with the outer casing 10 by spin removing vanes 20within an annular passage 21 between the cylindrical portions of theinner and outer casings. trio, with the wall 19 converging more than thewall 14 so as to form a diverging passage 23 between the walls 14 and19. n n I Supported on rails 24 which extend horizontally across theinterior of the inner casing 17, and which are secured at their ends tothe inner surface of the wall 18, are bearings 27 for rotary shaft 28.The shaft has attached to its upstream end hub 30 of centrifugal orradial rotor 31 having blades '32 secured to a back plate 33 and a frontplate 34. The rotor 31 has an axial inlet between the outer end of itsfront plate 34 and the inner end of the passage 12. The back plate 33 issecured to the hub 30 by rivets 36. A pulley 37 is attached to thedownstream end of the shaft 28.

In one embodiment of this invention, the

The walls 14 and 19 are concen- The inner casing 17 has a downstream endwhich is closed by end wall 38, and has an upstream end which is closedby end wall 39 except that the latter has a clearance opening 46 for theshaft 28. The wall 39 extends parallel to and is spaced axially from theback plate 33 of the rotor 31. The back plate 33 has a clearance opening48 around the shaft 28. V

An electric motor 40 has a base'41 attached to the top of the casing'10, and has a pulley 42 on its shaft aligned vertically with the pulley37. The walls 14 and 19 have a hollow fairing 45 extending therethroughin vertical alignment with the pulleys 37 and 42. Belts 47 on thepulleys 37 and 42 extend through the fairing 45.

An annular ringStl is attached to the upstream side of the wall 39around the opening 46, and converges within the space between'the wall39 and the back plate 3 3, towards the back plate. An annular ring 51 isattached to the downstream side of the back plate 33 around the opening48 and diverges within the space bet-ween the wall 39 and the back plate33, towards the Wall 39 and around the converging portion of the ring50'.

The hub 3i) has a central, circular recess 55, and has eight, equallyspacechapart, radially extending slots 56 which extend from the recess50 to the periphery of the hub.

In the operation of FIG. 1, the rotation of the rotor 31 by the motorAll, cause gas to be drawn in through the duct 13 and passage 12, anddischarged by the rotor, radially in a spiral. The gas discharged by therotor is turned axially by the inner and outer casings 17 and 10respectively, and passes through the annular passage 21. Near thedownstream end of the passage 21, the vanes 20 remove the spin from thegas, recovering pressure therefrom, the straightened-out gas passingthrough the passage 29 into the outlet duct 15.

For aerodynamic reasons, it is customary to place the bearings ofthis-type of fan in the inner casing 17 which is closed except for theconnection of its interior through the hollow fair-ing 45 to theatmosphere around the fan, and except for the clearance opening 46 inits end wall 39. When hot gas passes through the annular passage 21, theinterior of the inner casing 17 may be so heated that the bearings 27may be damaged. For preventing this, the hub 33 is provided with thecentral opening '55 and the radial slots 56 in its downstream side; Theslots act as radial fan blades when the hub is rota-ted, and draw airthrough the fairing '45, into the inner casing 17 around the bearings27, throughthe openings 46 and 48 into the blades of the rotor 31 whereit is discharged with the gas drawn through the passage 12 into theannular passage 21. This air cools the bearings '27.

Gas from the rotor 31 which leaks through the space between the backplate 33' and the wall 39 and would otherwise leak'into the inner casing17 and through the fairing '45 into the room in which the fan islocated, is prevented from passing into the inner casing by the sealrings 5% and 51 which deflect such gas towards the opening 48 in theback plate 33, and cause such gas to be induced into the opening 48 bythe ejector action of the air flowing through the opening 46 and theconverging portion of the ring 50 which acts as an ejector muzzle.

The embodiment of the invention shown by FIGS. 4 and 5 is similar tothat shown by FIGS. 1-3 except that instead of the central recess 55 andthe radial slots 56 being provided in the back side of the hub 30, andthe back plate '33 being provided with a central opening 48 around theshaft 28, the hub has eight holes 60 equally spaced-apart around theshaft drilled through the hub, with their'axes diverging away from theback side of the hub. 3 The inlets of the holes are at the back side ofthe rotor closely adjacent to. the adjacent portion of the shaft 28, theseal ring 51 extending around such inlets.

In the operation of FIGS. 4 and 5, the holes 60 act as auxiliary fanblades which when the rotor 31 is rotated, draw air from the atmospherearound the fan through the opening 46, the interior of the inner casing17 around the bearings 27, and the fairing 45. The seal rings 50 and 51act to prevent the escape of gas from the rotor into the atmospherearound the fan, as described in connection with FIGS. 1-3.

What is claimed is:

1. In a fan having an outer casing, circular in section, a smaller innercasing, circular in section, within said outer casing and concentrictherewith, said inner casing having a closed downstream end wall, andhaving an upstream end wall having :a central opening around the axis ofsaid casings, a radial flow fan rotor having a back plate adjacent toand extending substantially panallel to said upstream wall, said rotorhaving a front plate spaced from said back plate and having fan bladessupported between said plates, a hub attached to said back plate, ashaft attached to said hub and extending through said central openinginto said inner casing, bearings in said inner casing around said shaft,and having air supply means extending through said outer easing intosaid inner casing, the combination therewith of auxiliary fan means fordrawing air through said supply means into the interior of said innercasing and said central opening and discharging such air into said fanblades, said auxiliary fan means comprising passages in said hub havingair inlets adjacent to said shaft and having air outlets spaced fromsaid shaft larger distances than said inlets are spaced from said shaft,and sealing means for preventing the escape of gas from said rotorthrough said central opening, said sealing means comprising an annularring attached to said upstream end wall around said central opening, andhaving a first portion converging towards said hub and a second annularring attached to said rotor around said air inlets and having \a portionaround and spaced from said first portion.

2. In a fan having an outer casing, circular in section, a smaller innercasing, circular in section, within said inner casing and concentrictherewith, said inner casing having a closed downstream end Wall, andhaving an upstream end wall With a central opening around the axis ofsaid casings, a radial flow fan rotor having a back plate adjacent toand extending substantially parallel to said upstream end wall, saidrotor having a front plate spaced from said back plate and having fanblades supported between said plates, a hub having a portion attached tosaid back plate, a shaft attached to said hub and extending through saidcentral opening into said inner casing, bearings within said innercasing around said shaft, and having air supply means extending throughsaid outer casing into said inner casing, the combination therewith ofauxiliary fan means for drawing :air through said supply means into saidinner casing and through said central opening and discharging such airinto said fan blades, said auxiliary fan means comprising radial slotsin the downstream side of said hub portion, said plate having aclearance opening around said shaft at the inner ends of said slots, andsealing means for preventing the escape of gas from said rotor throughsaid central opening into said inner casing, said sealing meanscomprising an annular ring attached to said upstream wall around saidcentral opening and having a first portion converging towards said hub,and a second annular ring attached to said back plate around saidclearance opening and having a portion around and spaced from said firstportion.

3. In a fan having an outer casing, circular in section,

3 a smaller inner casing, circular in section, within said inner casingand concentric therewith, said inner casing having a closed downstreamend wall, and having an upstream end wall with a central opening aroundthe axis of said casings, a radial flow fan rotor having a back plateadjacent to and extending substantially parallel to said upstream endwall, said rotor having a front plate spaced from said back plate andhaving fan blades supported between said plates, a hub attached to saidback plate, a shaft attached to said hub and extending through saidcentral opening into said inner casing, bearings within said innercasing around said shaft, and having air supply means extending throughsaid outer casing into said inner casing, the combination therewith ofauxiliary fan means for drawing air through said supply means into saidinner casing and through said central opening and discharging such airinto said fan blades, said auxiliary fan means comprising a plurality ofspaced apart holes extending from adjacent to said shaft into thedownstream side of said hub through said hub with their axes divergingtowards said blades, and sealing means for preventing the escape of gasfrom said rotor through said central opening into said inner casing,said sealing means comprising an annular ring attached to said upstreamwall around said central opening and having a first portion whichconverges towards said hub, and a second annular ring attached to thedownstream side of said hub around said shaft, and having a portionaround and spaced from said first portion.

References Cited in the file of this patent UNITED STATES PATENTS390,508 Mosher et a1 Oct. 2, 1888 1,289,337 Wililey Dec. 31, 19181,429,538 Schetzel Sept. 19, 1922 1,604,328 Walker Oct. 26, 19262,601,030 Klein et al June 17, 1952 2,888,188 Hersh May 26, 19592,936,715 Southam et al. May 17, 1960 FOREIGN PATENTS 104,270 AustraliaJune 30, 1938 472,112 Germany Feb. 22, 1929 1,016,738 France Sept. 3,1952

1. IN A FAN HAVING AN OUTER CASING, CIRCULAR IN SECTION, A SMALLER INNERCASING, CIRCULAR IN SECTION, WITHIN SAID OUTER CASING AND CONCENTRICTHEREWITH, SAID INNER CASING HAVING A CLOSED DOWNSTREAM END WALL, ANDHAVING AN UPSTREAM END WALL HAVING A CENTRAL OPENING AROUND THE AXIS OFSAID CASINGS, A RADIAL FLOW FAN ROTOR HAVING A BACK PLATE ADJACENT TOAND EXTENDING SUBSTANTIALLY PARALLEL TO SAID UPSTREAM WALL, SAID ROTORHAVING A FRONT PLATE SPACED FROM SAID BACK PLATE AND HAVING FAN BLADESSUPPORTED BETWEEN SAID PLATES, A HUB ATTACHED TO SAID BACK PLATE, ASHAFT ATTACHED TO SAID HUB AND EXTENDING THROUGH SAID CENTRAL OPENINGINTO SAID INNER CASING, BEARINGS IN SAID INNER CASING AROUND SAID SHAFT,AND HAVING AIR SUPPLY MEANS EXTENDING THROUGH SAID OUTER CASING INTOSAID INNER CASING, THE COMBINATION THEREWITH OF AUXILIARY FAN MEANS FORDRAWING AIR THROUGH SAID SUPPLY MEANS INTO THE INTERIOR OF SAID INNERCASING AND SAID CENTRAL OPENING AND DISCHARGING SUCH AIR INTO SAID FANBLADES, SAID AUXILIARY FAN MEANS COMPRISING PASSINGS IN SAID HUB HAVINGAIR INLETS ADJACENT TO SAID SHAFT AND HAVING AIR OUTLETS SPACED FROMSAID SHAFT LARGER DISTANCES THAN SAID INLETS ARE SPACED FROM SAID SHAFT,AND SEALING MEANS FOR PREVENTING THE ESCAPE OF GAS FROM SAID ROTORTHROUGH SAID CENTRAL OPENING, SAID SEALING MEANS COMPRISING AN ANNULARRING ATTACHED TO SAID UPSTREAM END WALL AROUND SAID CENTRAL OPENING, ANDHAVING A FIRST PORTION CONVERGING TOWARDS SAID HUB AND A SECOND ANNULARRING ATTACHED TO SAID ROTOR AROUND SAID AIR INLETS AND HAVING A PORTIONAROUND AND SPACED FROM SAID FIRST PORTION.